R/get_cog.R

In Yuki-Kanamori/ggvast: ggvast is a R package for visualisations of the VAST outputs

#' Calculate the lon/lat of COG
#'
#' get the lon/lat of COG from nominal data
#' @param data Data_Geostat
#'
#' @importFrom dplyr filter
#' @importFrom dplyr select
#' @importFrom plyr ddply
#' @importFrom plyr .
#' @import dplyr
#' @import magrittr
#'
#' @export
#'

get_cog = function(data){

  #single-species
  if(!("spp" %in% names(data))){
    #cog_lon = sum_{year}{Catch_KG*Lon}/sum_{year}{Catch_KG}を計算
    dg = DG %>% select(Catch_KG, Lon, Lat, Year) %>% mutate(cog_lon = Catch_KG*Lon, cog_lat = Catch_KG*Lat)

    lon_nume = ddply(dg, .(Year), summarize, nume = sum(cog_lon))
    lon_deno = ddply(dg, .(Year), summarize, deno = sum(Catch_KG))
    cog_lon = merge(lon_nume, lon_deno, by = "Year") %>% mutate(lon = nume/deno) %>% select(Year, lon)

    lat_nume = ddply(dg, .(Year), summarize, nume = sum(cog_lat))
    lat_deno = ddply(dg, .(Year), summarize, deno = sum(Catch_KG))
    cog_lat = merge(lat_nume, lat_deno, by = "Year") %>% mutate(lat = nume/deno) %>% select(Year, lat)

    cog_nominal = merge(cog_lon, cog_lat, by = "Year") %>% mutate(spp = 1)
  }

  #multi-species
  else{
    #cog = sum_{year}{Catch_KG*Lon}/sum_{year}{Catch_KG}を計算
    df = DG %>% select(Catch_KG, Lon, Lat, Year, spp) %>% mutate(cog_lon = Catch_KG*Lon, cog_lat = Catch_KG*Lat)

    lon_nume = ddply(df, .(Year, spp), summarize, nume = sum(cog_lon))
    lon_deno = ddply(df, .(Year, spp), summarize, deno = sum(Catch_KG))
    cog_lon = merge(lon_nume, lon_deno, by = c("Year", "spp")) %>% mutate(lon = nume/deno) %>% select(Year, lon, spp)

    lat_nume = ddply(df, .(Year, spp), summarize, nume = sum(cog_lat))
    lat_deno = ddply(df, .(Year, spp), summarize, deno = sum(Catch_KG))
    cog_lat = merge(lat_nume, lat_deno, by = c("Year", "spp")) %>% mutate(lat = nume/deno) %>% select(Year, lat, spp)

    cog_nominal = merge(cog_lon, cog_lat, by = c("Year", "spp"))
  }
}